Digital imaging systems, such as copiers, facsimile machines, and scanners have become commonplace. Such systems scan an image into an analog signal, and convert the analog signal into a digital signal for processing or storage. This analog to digital conversion takes place in a digitizing channel of the system. Typically, an analog front end (AFE) circuit is employed in the digitizing channel, for amplifying and digitizing the analog signal. AFEs often include circuitry for gain calibration, in addition to converting the analog signal into a digital signal. Gain calibration may be employed to (a) match the level of the incoming analog signal to the available dynamic range of the digitizing channel to achieve improved signal-to-noise ratio (SNR), and (b) in color systems, to balance the relative levels of the red, green, and blue (RGB) digitizing channels for proper color interpretation.